Method and apparatus for wrapping articles in stretchable sheet material



Oct. 28, 1952 c. E. CLOUD 2,515,200

Y METHOD AND APPARATUS FOR WRAPPING ARTICLES IN STRETCHABLE SHEETMATERIAL l6 Sheets-Sheet 1 Filed Feb. 9, 1949 Oct. 28, 1952 c. E. CLOUD2,615,200

METHOD AND APPARATUS FOR WRAPPING ARTICLES IN STRETCHABLE SHEET MATERIALFiled Feb. 9, 1949 16 Sheets-Sheet 2 Oct. 28, 1952 c. E. CLOUD 12,615,200

METHOD AND APPARATUS FOR WRAPPING ARTICLES IN STRETCHABLE SHEET MATERIALFi led Feb. 9, 1949 1e Sheets-Sheet s Oct. 28, 1952 E CLOUD 2,615,200

C. METHOD AND APPARATUS FOR WRAPPING ARTICLES IN STRETCHABLE SHEETMATERIAL Filed Feb. 9, 1949 16 Sheets-Sheet 4 Oct. 28, 1952 c. E. CLOUDMETHOD AND APPARATUS FOR WRAPPING ARTICLES IN STRETCHABLE SHEET MATERIALFiled Feb. 9, 1949 16 Sheets-Sheet 5 azmzed 67W C. E. CLOUD METHOD ANDAPPARATUS FOR WRAPPING ARTICLES IN Oct. 28, 1952 STRETCHABLE SHEETMATERIAL l6 Sheets-Sheet 6 Filed Feb. 9, 1949 gill/l Oct. 28, 1952 c. E.CLOUD METHOD AND APPARATUS FOR WRAPPING ARTICLES IN STRETCHABLE SHEETMATERIAL Filed Feb 9, 1949 16 Sheets-Sheet '7 nn/@2251 M 67 W Zama C. E.CLOUD METHOD AND APPARATUS FOR WRAPPING ARTICLES IN Oct. 28, 1952STRETCHABLE SHEET MATERIAL l6 Sheets-Sheet 8 Filed Feb. 9, 1949 Oct. 28,1952 c. E. CLOUD 2,615,200

METHOD AND APPARATUS FOR WRAPPING ARTICLES IN STRETCHABLE SHEET MATERIALFiled Feb. 9, 1949 16 Sheets-Sheet 9 Oct. 28, 1952 c. E. CLOUD METHODAND APPARATUS FOR WRAPPING ARTICLES IN .STRETCHABLE SHEET MATERIAL l6Sheets-Sheet 10 Filed Feb. 9, 1949 Oct. 28, 1952 E. CLOUD METHOD ANDAPPARATUS FOR WRAPPING ARTICLES IN STRETCHABLE SHEET MATERIAL Filed Feb.9, 1949 16 Sheeis-Sheet l1 E?! n: I

Oct. 28, 1952 METHOD Filed Feb. 9, 1949 c. E. CLOUD 2,615,200 ANDAPPARATUS FOR WRAPPING ARTICLES IN STRETCHABLE $HEET MATERIAL l6Sheets-Sheet 12 Oct. 28, 1952 c E CLOUD 2,615,200

METHOD AND APPARATUS. FOR WRAPPING ARTICLES IN STRETCHABLE SHEETMATERIAL Filed Feb. 9, 1949 16 Sheets-Sheet 13 zz -zj I LUG o- PINION:91 (FIGJQ) LUG ON FLOATING PIN- 9 f% PINION :as/ 97 Xw m Oct. 28, 1952c. E. CLOUD 2,615,200

METHOD AND APPARATUS FOR WRAPPING ARTICLES IN .STRETCHABLE SHEETMATERIAL Filed Feb. 9, 1949 16 Sheets-Sheet l4 CLAMP PLATE HEATER PAD Z,y26' [a CONSTRICTIONS DRAW /4 CYLINDER vAc. PUMP VAC. TANK 81 //0v. l M

2/3 or r 2/0 *fi-zm Z. Q" Z I I A A E I 1 1 23/ n 1 I Q 0 I 1 ++r-. O ol A l w 23.2 1| I l r I 231' I! 1 I U i I II I I I 3 I W Viva/@133 L-LlOct. 28, 1952 c. E. CLOUD METHOD AND APPARATUS FOR WRAPPING ARTICLES INSTRETCHABLE SHEET MATERIAL l6 Sheets-Sheet 15 Filed Feb. 9, 1949 4.illilfflh Oct 28, 1952 METHOD AND APPARATUS FOR STRETCHABLE SHE FiledFeb. 9, 1949 iz -ja Patented Oct. 28 1952 METHOD AND APPARATUS FORWRAPPING ARTICLES IN STRETCHABLE SHEET 111A- TERIAL Charles E. Cloud,Wilmette, 111., assigner to William S. Cloud, Wilmette, 111.

Application February 9, 1949, Serial No. 75,322

21 Claims.

This invention relates to methods of wrapping articles in stretchablesheet material and to apparatus for practicing such methods.

In practicing some aspects of my invention, it is necessary that thesheet material used be stretchable, or be capable of being renderedstretchable by the application thereto of heat, chemicals or othersoftening means. In some practices of my invention, the sheet materialis also preferably transparent, moisture-proof, impermeable to air andcertain other gases, and heat-scalable; that is, capable of havingengaging portions fused together when heated. One such sheet materialwhich has all of these characteristics suitable for practicing myinvention, and which is commercially available, is a flexibletransparent stabilized rubber hydrochloride film. Such material iswell-known in the trade under the name of Pliofilm, being manufacturedby the Goodyear Tire & Rubber Company of Akron, Ohio, under Patent No.1,989,632. The stabilization seems to be desirable for lasting qualitiesof the film, rather than being necessary for this invention.

There are numerous, well-recognized advantages in wrapping articles-inmaterial which con forms to the exact size and shape of the articles,especially where the material is transparent. Several methods have beendevised to do this. One, as described in Patent No. 2,312,049, involvessuspending a stretchable sheet in horizontal position over a metalframe, manually forcing the article against the sheet to form a pockettherein containing the article, manually twisting the article and thesheet to close and seal the pocket, and severing the excess portion ofthe sheet by a knife or other cutting means.

A fully automatic apparatus for practicing another method is describedin Patent No. 2,403,- 482.

One of the objects of my invention is to provide methods and means forwrapping articles in material which conforms to the exact size and shapeof the articles, but which eliminate the hand operations, reduce cost,increase speed and simplify the apparatus.

Other objects and advantages will appear from the following descriptionand from the drawings.

Two general embodiments of the invention, selected for the purposes ofillustration, are shown in the accompanying drawings, in which:

Figure 1 is a fragmentary and simplified side elevation of the machine.

Fig. 1A is a somewhat diagrammatic sectional view of a modification ofthe invention for spot heating of the film.

Fig. 2 is a transverse section approximately on the irregular line 22 ofFig. 1, some parts being omitted for clarity.

Fig. 3 is a detail section showing the mechanism for raising andlowering sleeves 4| and associated parts.

Fig. 3A is a detail section showing alternative apparatus for openingand closing bottom plate 4:1.

Fig. i is a detail section showing the mechanism for raising andlowering holding plate l7.

Fig. 5 is a detail section showing the mechanism for driving sprocketchain 4, which feeds the sheet material.

Fig. 6 is a horizontal sectional view looking downwardly and takenapproximately on line 6-45 of Fig. 1, showing the mechanism for drivinggeared rings til, the parts being moved from the Fig. 1 position.

Figs. 7 to 12 are diagrammatic views illustrating the various changedpositions in the operation of wrapping a spherical object.

Fig. 13 is a view showing the upper face of a sleeve type of closingdevice as a modified form of the invention.

The remaining figures show a preferred modification of the invention asfollows:

Fig. 14 is a view of this preferred form of the invention from above.

Fig. 15 is a diagrammatic side representation of the structure of Fig.14.

Fig. 16 is a side view of the structure shown in Fig. 14, some partsbeing omitted for clarity.

Fig. 1'7 is a vertical sectional view taken approximately on the linelL-dl of Fig. 16, the lower part of the apparatus being omitted.

Fig. 18 is a fragmentary detail sectional View taken approximately onthe line iii-l8 of Fig. 17.

Fig. 19 is a fragmentary longitudinal vertical sectional View takenapproximately on the line E@i of Fig. 17.

Fig. 20 is a fragmentary transverse vertical sectional View takenapproximately on the line iii-2b of Fig. 16.

Fig. 21 is a view looking down the choke rings removed from the machine,the dotted line showing the position of the strands when one ring hasbeen turned with respect to the other to stretch the bands across thespace.

view illustrating a modification of the invention in which the filmseals directly against the upper edge of the vacuum sleeve.

Fig. 23 is a horizontal sectional view taken approximately on the line23-23 of Fig. 19 to show the support of the choke ring.

Fig. 24 is a fragmentary sectional view taken approximately on the line2424 of Fig. 23.

Fig. 25 is a fragmentary detail view showing the cam control of thevacuum lines for operating the vertically moving parts of the apparatus.

Fig. 26 is a diagrammatic representation of the vacuum system.

Fig. 27 is a diagrammatic representation of the electrical system.

Fig. 28 is a fragmentary vertical sectional View showing an adapter forreducing the effective size of the main vacuum chamber.

Figs. 29 through 36 are diagrammatic vertical sectional views showingthe successive stages of the wrappin of one article.

Fig. 37 is a fragmentary sectional view showing a modified form of theinvention cutting the material along a smaller line.

Fig. 38 is a diagrammatic view showing the way in which the structure ofFig. 37 save-s material.

Although the law requires a full and exact description of at least oneform of the invention, such as that which follows, it is, of course, thepurpose of a patent to cover each new inventive concept therein, nomatter how it may later be disguised by variations in form or additionsof further improvements; and the appended claims are intended toaccomplish this purpose by particularly pointin out the parts,improvements or combinations in which the inventive concepts are found.

General operation vIn the forms of the invention shown in the drawings,a web or sheet 6 of stretchable material is drawn from a roll I, to aposition over rings or openings ill in plate il. There the sheet isfirmly clamped or held. The portions of the sheet immediately over theopenings are forced down through them to form pockets into which thearticles are deposited. The tops of the pockets are closed, and thepocket portions of the sheet containing the wrapped articles are cutout. The balance of the sheet is then advanced and the process repeated.

Sheet feed (Fig. 1)

A roll I of sheet material 6 rests on rollers 2 and 3. This arrangementpermits greater ease and speed in the changing of rolls than does theusual mounting and is preferred in some respects, although it was notconceived by me. Roller 3 is driven intermittently through a sprocket bysprocket chain 4, in timed relation to the movement of heating drum 8and wringer rolls I 2, the combined movement of which advances sheetmaterial 6. If the sheet material is not stretchable. in its naturalcondition, it is now exposed to chemicals or heat to so render it.Although methods and apparatus for treating sheet material to render itstretchable are old in the art, I have illustrated one method of heatingthe sheet material, Which is appropriate for common Pliofilm, indicatedabove as being suitable for practicing my invention. Other methods ofheating are illustrated in Figs. 1A, and 14 to 27, and are disclosed inPatents Nos. 2,312,049 and 2,403,482. In themethod here illustrated, thesheet 6 passes under guide roller '1, around heating drum 8 and underguide roller 9. Heating drum 8 is pref erably driven intermittently bychain 4, and is maintained at the proper temperature by steam or anyother convenient means. From the guide roller 9 the sheet is drawn byfeed rolls l2 over openings ID in plate or support H. The sheet pauseswhile portions of the sheet are forced through holes ID to form pocketsin which articles are wrapped. After the wrapped articles have beensevered from the web, the remainder of the web is drawn on by feed rolls[2, at least one of which is intermittently driven by chain 4. Thisremainder or scrap may pass from the feed rolls I2 to suitable wind-upmeans such as revolving core, which may be located outside of the limitsof the drawings. The sellers of a particular sheet material will be ableto advise the approximate temperature to which it should be heated to bereadily stretchable, and the heating should be adjustable so that theexact optimum temperature can be reached by observing the operation. Byproper placement of the openings in plate H, and proper advancing of thesheet material, the remainder (scrap) thereof is preferably reduced toas little as is consistent with proper handling and disposal thereof,which may vary with the sheet material being used.

The apparatus for activating sprocket chain 4 and for the timing thereofis best illustrated in Figs. 1 and 5. Main cam shaft 2| which, directlyor indirectly, controls all parts of the machine, is driven constantlyby sprocket chain 22, which is connected in the usual manner to a motor(not shown). As shown in Fig. 5, a cam 24 is affixed to shaft 2!, whichrotates in bearing blocks 23. This cam 24 actuates cam follower or lever26, pivotally supported by shaft 21. The movement of lever 26, caused bycam 26, controls the movement of link .25, pivoted on shaft 28, andwhich intermittently drives sprocket chain 4. The intermittent drive isaccomplished by means of any suitable overrunning clutch device,typified by roller 29. This mechanism is biased for return movement bytension spring 30, of which one end is attached to the frame and theother to lever 26.

Sheet holding A fresh portion of sheet 6 having been advanced to aposition over rings or openings It] in plate I I, mechanism becomesefiective for firm- 1y clamping or holding this portion over theopenings while the portions of the sheet immediately over the openingsare forced down through them to form pockets and until after the pocketshave been filled, closed and cut off. Methods of holding sheet material,and apparatus for so doing, are old in the art. It can be done by eitherfluid or mechanical pressure. I have shown one form of apparatus fordoing this in the drawings, especially Fig. 4.

Slidably mounted on vertical rods or shafts l 6, and held horizontallythereby, is a top or holding plate [1, containing, as best illustratedin Figs. '7 to 12, openings 20 corresponding in size and shape to theopenings It in plate ll. Plate I1 is biased downwardly by tensionsprings [8, of which one end is attached to the frame and the other tocam followers or levers [9, which are adapted to regulate the verticalmovement of plate I! by means of links 15. Levers l9 are pivotallymounted on shaft 21 and are uniformly controlled by having one end ofeach ride on cams 3|, carried by shaft 2|, which cams are so shaped asto allow or assist tension springs i8 to lower plate ll, when theforward motion of sheet E5 has ceased, to clamp the sheet between plateil and plate H and hold it while pockets are formed, filled, closed andcut off, at which time they raise plate l1. Although I prefer to havetwo sets of cams affixed to opposite ends of shaft ii, for purposes ofsimplification only one set of these cams, and their related levers, areshown on certain of the drawings.

To avoid the ossibility of rupturing sheet 6, and to secure a firm gripon the edges of the pockets where the stress on the held portion of thesheet will be greatest, I prefer to ttach to the lower edges of theopenings 2% in plate ll rings 32 of sponge rubber or other resilient andnon-abrasive material. This is best shown in Figs. 7 to 12. It may alsobe desirable to round off the upper edges of the openings ill in plate il, to prevent rupturing.

Pocket forming Fresh portions of sheet 6 being held over the openingsill in plate ii, there becomes effective the mechanism for forcing theseportions through the openings to form pockets.

Pockets have heretofore usually been formed by fiuid pressure, or bymechanical pressure, the latter in some cases exerted by the articleswhich are ,to be enclosed in the pockets. Combinations of these methodshave been used. I prefer to make the initial forming of the pockets byfluid pressure and thereafter to further enlarge them by a grippedstretch (moving apart two positively held parts of the pocket). This ispreferred for a number of reasons, including the following:

First, the use of any one of the methods alone is inefficient in its useof sheet material. It has long been recognized that a vacuum isprogressively more effective toward the center or bottom of a pocketcreated by it, so that the material from which the pocket is formedbecomes progressively thinner toward the center. Thus, the use of acuumalone inherently prevents the forming of the largest size pocket whichcould be made from a given area of material, and the walls of the pocketthat is formed will be of widely varying thickness and strength. It hasalso been recognized that, due in part to friction, stretching by amember exerting mechanical pressure against the center stretches mostlythe portions away from the center or bottom of a pocket formed by it, sothat it has the same inherent limitations although the thinner portionsof pockets formed by it are placed differently. Stretching by the weightof an object to be wrapped has the same effect as stretching bymechanical pressure, and should be considered as merely a form thereof.Obviously, as the two forms of stretching produce opposite results, theysomewhat offset one another, but the results are believed to vary.Different surfaces used for the mechanical stretching permit varyingslippage with different amounts and distribution of stretching. Byfollowing the fluid stretch with a gripped stretch as in the presentinvention such slippage is avoided. The results are more dependableandgreater stretching of the neck portion of the pocket seems practical.It is to be understood that apparatus for forming pockets by eitherfluid pressure or mechanical pressure, either alone or in anycombination, could be used with some features of the present invention.

The preferred method of pocket forming, as well as some prior methods,has the advantage of preforming the pockets. One broad field in the 6,packaging art includes the packaging of liquids. Liquids cannot bepackaged without difficulties unless either a preformed pocket isavailable or dams are provided. Similar difficulties are encountered inthe packaging of loose material or powder, such as cement, tea orbouillon powder, and in the packaging of gases. All of these types canbe readily packaged by the apparatus illustrated and described, with asuitable pocketiilling device.

Slidably mounted on vertical rods or shafts l6, and held horizontallythereby, is horizontal casting or beam 36 (Fig. 2). As best seen in Fig.3, the vertical movement of beam 3-5 is governed by cams 38 attached toshaft 2i and which rock cam followers or levers t'l, pivotally mountedon shaft 27. The end of levers 3T remote from the cams 38 are attachedto beam 38-by links ill. Beam 36 is biased upwardly by tension springs39 (Fig. l) of which one end is attached to the frame and the other tolevers Te-l. Cams 38 are so shaped as to allow tension springs as toraise beam 33 approximately as the sheet is gripped between plates 5 land ll, the cam lowering beam 36 when the mechanical stretching is to bedone. Rigidly attached to beam 36 are tubes or sleeves H, the insidediameter of which, as best illustrated in Figs. (-12, corresponds insize and shape to the openings in plates H and F. The tubes 4| may beheld by set screws in collars 2 8 preferably cast as parts of beam 36.Tubes ii are so positioned that when beam 36 is fully raised asubstantially air-tight contact is made between the tops of tubes M andthe bottom edges of the openings in plate ii. To ensure the tightness ofthis contact, it may be desirable to cement gaskets M to the lower edgesof the openings it in plate I I. Also attached to beam 36, by hinges ls,is a bottom plate 3 adapted to be swung up to form an air-tight closureat the bottoms of tubes ll. Here again, to ensure the tightness of thecontact, it may be desirable to surface plate with a layer of spongerubber d8 having an impervious upper face. The term shell may be used todesignate the pocketing unit which is illustrated as embodying mainlythe tube ll, this term being especially suitable when it is. desired toimply that the bottom is closed during the draw-down of the pocketwithout specifically mentioning the bottom plate id. If fragile articlesor ones which bruise easily are to be dropped into the pockets, it maybe desirable to add a second layer of sponge rubber ti'i, which may beof such size and shape that it will fit into the bottoms of the tubes.Tubes M are connected with a vacuum pump (not shown) by vacuum hose 6%)(Fig. 1) through ports 5i (Figs. 2, 7 and 8) which lead through thecontainers id and sleeves ii. The vacuum pump can operate continuously.

As the sheet 6 is being gripped between plates H and H, levers 3'5,riding on cams 3S, allow tension springs 39 to raise sleeves fill intocontact with plate H. The movement of levers 3'! also indirectlyoperates bottom plate i l attached by hinge 43 to beam 35. The end ofbottom plate l t, extending beyond hinges d3, strikes resilientadjustable stops 52, swinging up bottom plate 5 5 into contact with thebottoms of tubes ill. To ensure closure at all points, a separate bottomplate may be provided for each sleeve ill, each actuated by a separatestop 52.

An alternate apparatus for operating bottom plate M is shown in Fig. 3A.There a tension spring 53 is attached at one end to the frame and at theother to a rope, the other end of which extends through and is knottedabove the end of each bottom plate 44. This will operate in the samemanner as will set stops 52. The spring 53 or spring stop 52 ensures aclosing pressure on plate 44 in spite of variations in the parts, andadjustments for spring 53 may be provided as shown for stop 52.

At this time the vacuum becomes effective through ports to draw sheet 6into sleeves 4|, as shown by comparing Figs. 7 and 8. On the inside ofsleeves 4|, as shown in Figs. 7-12, are mounted rings 56 and 57,supporting screens 58. Screens 58 prevent the sheet 6 from being pulledthrough the rather large ports 5| and thus being ruptured. It will beobserved that in each tube 4| the film seals against rings 58 and 51thus closing off the vacuum chamber formed between screen 58 and tube4|. This shuts off the vacuum from below ring 51 so that expansion ofthe pocket by vacuum is automatically terminated in about the positionseen in Fig. 8. The vacuum stretch having been completed, cams 38 andlevers 31 lower sleeves 4|. This does not break the Vacuum holding thepocket down in sleeves 4| because each pocket is sealed against ring 56by the vacuum. As shown in Fig. 9, lowering sleeves 4|, in which thepockets are held by vacuum, will cause those portions of sheet 5 beingheld between plate II and rings 55 to be further stretched. Rings 56extend inwardly beyond screens 58, to give a snubbing effect which,assisted by the roughness of the screen, prevents the film from slippingand perhaps breaking the vacuum during the mechanical sleeves 4| andbeam 36 are lowered, stops 52 cease to hold bottom plates 44 against thebottoms of sleeves 4|; but the bottom plate continues to be held up bythe vacuum within the sleeves 4!.

Pocket filling The pocket now being fully formed, the articles aredeposited therein. As methods of feeding articles into pockets, andapparatus for so doing, are old in the art, it is deemed unnecessary tode scribe the diagrammatically represented feeder 50, the type of whichwill vary according to the particular article or type of article to bepackaged. The form of the invention shown in the drawings is evenadapted to package powders, liquids and gases, if vertically moving,possibly tapered nozzles are used for feeding. When necessary to preventloss of contents, the necks of the pockets may be constricted in twosteps, the first (before filling the pockets) closing the neck about thenozzles, and the second closing the necks completely as the nozzles arewithdrawn.

Pocket closing To close with greater speed and efficiency, and to allowthe use of one closing mechanism regardless of the size or type of thecontents of the pockets, I prefer to use the pocket closing mechanismshown in Figs. 1, 2, and 7-12. Rotatably mounted around the upperportions of sleeves 4|, at the outside thereof, are geared rings 6|, theteeth of which mesh so that all such rings may be driven through one ofthem. At spaced intervals endless bands or strips 62 of rubber or othersuitable material are attached between rings 6| and the edges of theopenings It in plate These strips do not have to be of stretchablematerial, although that permits some simplificastretch. As

tion and is preferred. The twisting of rings 6| forces these strips 62from a separated, substantially vertical position, as shown in Figs. 2,and 7-9, into an intersecting, substantially horizontal position, asshown in Figs. 6, 10 and 11, closing the pockets surprisingly tightly.

The sealing of the pockets may be effected when the pockets are closed,if sealing is desirable. If the sheet material used is the common,nonstretchable Pliofilm, it must have been previously heated to renderit stretchable, and the mere closing of the pockets will seal them,since they will not have been stretched excessively or allowed to standlong enough to lose their tackiness. To heat-seal certain other sheetmaterials, it may be necessary to use strips 62 of resistance wire orother material which will conduct heat and to heat them by electricityat the moment they effect a closure of the pockets. When using othermaterials which are not heat-scalable, it may be desirable to hold theclosure by glue, cord or tape. Apparatus for this is old in thepackaging art.

One apparatus which may be used to twist the rings 6| is best shown inFigs. 1 and 6. Mounted in a position to be tripped by the lowering oflever 31 is switch 66 for valve control unit G1, which admits air tocylinder 68, forcing out rack or geared rod 69, which is meshed withgear H mounted on vertical rod or shaft 12, rotatably mounted on theframe, and having mounted thereon gear 73, which is meshed with one ofgeared rings 6|. The air cylinder and controls are preferably of thetype, commercially available, which forces rod 69 first out and then in,thus returning strips 62 to their substantially vertical positions, asshown in Fig. 12, so that the apparatus is readied for the nextarticles. This type of apparatus permits control of the amount oftwisting which is done, which may be necessary if, for example, strips62 are of resistance wire or other relatively non-stretchable material.

For strips 62 can be substituted a tube 15 of rubber or other suitablematerial, which may be secured to the choke rings 6| by cement, clampingrings, or both. The twisting in such case will cause the tube to form anannular sheet over the pocket, further twisting causing this sheet toconstrict the aperture therethrough and eventually close it, as seen inFig. 13, squeezing anything within the aperture.

It is believed that the strength of the vacuum holding the film againstthe screen 58 can be so selected that the constrictor will pull the filmaway from the ring 56 and screen 58 enough to break the vacuum. In anyevent, the strength of the vacuum should be adjustable. This may beaccomplished by providing an adjustable relief valve or by providingadjustable means for determining the speed of the vacuum pump, assumingit is of a type in which the pressure varies with speed.

To safeguard against the possibility that the vacuum may not bedependably broken in this way, it is preferred at present to provideautomatic means for breaking the vacuum in timed relation to theremaining apparatus. For example, a valve to the vacuum line could beopened automatically by a cam on shaft 2|.

It is to be noted that the closing or constricting apparatus describedis admirably adaptable for remote uses such as for holding objects and,in the case of the sleeve form, for use where diaphragm closers arenecessary, as in cameras.

